Fractionator



Feb. 10, 1970 v P. s. HOEFER 1 7 3,494,508

- FRACTIONATOR Filed May 10, 19 8 INVENTOR.

Peter S Hoefer 73 BY w N 2 k Attorneys United States Patent 3,494,508FRACTIONATOR Peter Stanton Hoefer, 2609 California St., San Francisco,Calif. 94115 Filed May 10, 1968, Ser. No. 728,216 Int. Cl. B67b 7/24;B04b 9/12 US. Cl. 222--82 8 Claims ABSTRACT OF THE DISCLOSURE Afractionator for the removal of gradient layers from preparativeultra-centrifuge tubes. The tube is retained by a structure including abottom plate with three upwardly extending posts upon which spacer ringsare slid. These provide abutments for adaptor rings into which thecentrifuge tube is set. A rubber cap with a dome shaped surface sealsthe top of the centrifuge tube and is held against the tube by ahold-down tube which extends through a twist-lock top plate fastened tothe upwardly extending posts. A knurled knob fastens the hold-down tubeto maintain pressure on the centrifuge tube. The bottom of thecentrifuge tube rests on a rubber washer which covers an aperturethrough the bottom plate. The washer and tube bottom are pierced by aneedle in a chuck assembly as it is threaded into the bottom plate. Thecentrifuge tube may be drained by gravity downwardly or a dense liquidpumped into the bottom through the needle to cause upward flow throughthe hold-down tube.

BACKGROUND OF THE INVENTION The present invention is directed to afractionator for the removal of gradient layers from preparativeultracentrifuge tubes.

In the field of removing gradient layers from ultracentrifuge tubespresent devices are inadequate in that separate units are necessary fordifferent size centrifuge tubes. Moreover, the construction of the unitsvary depending on whether the layers are to be drawn out of the top ofthe tube (termed upward flow) or from the bottom of the tube (termeddownward fiow). Prior art devices, moreover, have involved, complex andtime consuming adjustments.

OBJECTS AND SUMMARY OF INVENTION It is therefore a general object of theinvention to provide an improved fractionator for the removal ofgradient layers from preparative ultra-centrifuge tubes.

It is another object of this invention to provide a fractionator of theabove type which is usable with tubes of many different sizes.

It is another object of the invention to provide a fractionator of theabove type which is suitable for both upward and downward flow.

It is another object of the invention to provide a fractionator which issimple in operation.

In accordance with the above objects there is provided a fractionatorfor the removal of gradient layers from preparative ultra-centrifugetubes which includes a bottom plate having an apertured center portionadapted to receiving one of the tubes. A plurality of support postsextend upwardly from the bottom plate and define a cylindrical volumehaving a predetermined diameter. Spacer means are provided which areadapted to be slid over the posts and provide abutments. A plurality ofadaptor rings having an outer diameter substantially equal to thepredetermined diameter of the cylindrical volume and an inner diameterequal to the tube diameter rest on the abutments provided by the spacermeans. Finally, means are provided which are adapted to hold down thetube 3,494,508 Patented Feb. 10, 1970 against the center portionincluding a cap for sealing the tube, a top plate afiixed to the postsand a rigid tube extending through the top plate into contact with thesealing cap along with means for fixedly securing the rigid tube to thetop plate.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of afractionator embodying the present invention;

FIGURE 2 is a cross-sectional view in exploded format takensubstantially along the line 22 of FIGURE 1; and

FIGURE 3 is a cross-sectional view taken substantially along the line 33of FIGURE 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to FIGURE 1,a bottom plate 11 is provided with a recessed center portion 12 havingan inset rubber washer 13. A centrifuge tube 14 which is to befractionated has its bottom resting upon the rubber washer. Bottom plate11 also has a central aperture below the rubber washer 13 which will bediscussed below.

Extending upwardly from bottom plate 11 are three vertical posts 16 onwhich are slid aluminum spacer tubes 17. The top portion 17a of thesespacer tubes provide abutments on which adaptor rings 19 rest. Eachadaptor ring has an outer diameter which is determined by the diameterof the cylindrical volume encompassed by posts 16 and an inner diameterdetermined by the diameter of the particular centrifuge tube which is tobe fractionated. Thus, different size tubes may be accommodated byvarying the inner diameter of adaptor rings 19 and centrifuge tubes ofdifferent lengths may be accommodated by varying the number of spacers17 and adaptor rings 19 used. For example, if a longer tube is to beused an additional set of spacers 17 and adaptor rings 19 would beadded. Conversely, if a shorter tube is used the lower-most adaptor ringmight be placed directly against bottom plate 11 and only one set ofspacers 17 used.

Tube 14 is retained against the rubber washer 13 by hold-down meanswhich include a silicone rubber sealing cap 21, a rigid tube 22, and atwist-lock top plate 23. As shown in greater detail in FIGURE 3, the cap21 has a conical or dome shaped undersurface 24 which mates with the topof tube 14 to provide an air and liquid tight seal. A center aperture 26of cap 21 communicates with tube 22 which is inset into recessed portion27 of cap 21. This also provides an air tight seal between rigid tube 22and cap 21. Top plate 23 is secured to posts 16 by a twisting typeaction. Plate 23 is placed on the posts through its oversize holes 28and then rotated into locking abutment with undersize holes 29 in theplate with respect to corresponding grooves in the posts 16.

Rigid hold-down tube 22 is fixedly secured to top plate 23 to providefor pressure by cap 21 against the tube 14. Pressure is first applied totube 22 and then it is secured to the top plate by a knurled knob 31which extends through the plate into contact with tube 22.

A horizontal rod 32 is afiixed to bottom plate 11 to serve as a supportarm for use with standard laboratory apparatus.

In order to either draw liquid out of the tube 14 from the bottom toprovide a downward flow or to create an upward pressure in the tube forupward fiow through tube 22, means are provided for penetrating thecentrifuge tube with a needle 33.

In general, and referring to FIGURE 2 as well as FIGURE 1, needle 33 isinserted into a needle holding chuck assembly generally indicated at 34which allows the needle to protrude from the chuck assembly apredetermined amount. The chuck assembly is then screwed into a centeraperture 36 of bottom plate 11 to cause the needle to penetrate rubberwasher 13 and the bottom of tube 14 to reach the indicated layers ofliquid 37 in the ultra-centrifuge tube.

More specifically, chuck assembly 34 includes a knurled nut 38 having athreaded receptacle portion 39. A sleeve 41 with deformable jaws 42 isfitted into receptacle 39 with jaws 42 abuting against the end of thereceptacle. A main chuck knob 43 includes exteriorly threaded sleeve 44which is affixed to main knob 43 by a lock washer 46. An exteriorthreaded portion 47 of sleeve 44 mates with the interior threads ofaperture 36. Portion 47 includes an internal cam surface 48 which wedgesagainst the jaws 42 to hold needle 33. Threaded portion 47 allows thechuck assembly 34 to be screwed into aperture 36 so that needle 33penetrates rubber washer 13 and the bottom of tube 14.

OPERATION To provide a downward flow (that is, taking the gradientlayers out of the bottom of tube 14) an ultra-centrifuge tube containinggradient layers is placed in the apparatus with the spacers and adaptorrings. The cap normally used for centrifugation is removed and thesilicone rubber cap 21 placed on the tube. The twist-lock cap 23 is thenplaced over the posts and twisted. Hold-down tube 22 is placed throughthe hole in the twist-lock cap and seated in the recess 27 of thesealing cap 21. Downward presure is applied to hold-down tube 22 and theknurled knob 31 on top plate 23 is tightened. This holds tube 14 inplace and creates an air and liquid tight seal at the rim of thecentrifuge tube. A leak-proof seal is also created at the bottom of thecentrifuge tube in relation to rubber washer 13.

Next a needle 33 of the proper gauge is procured. For example, a small20 gauge needle is best for thin-wall cellulose acetate tubes; the large18 gauge needle is best for the tougher polyalomer tubes. The needle isinserted in the chuck asembly 34 by loosening the small knurled nut 38in the needle-holding chuck. Of course, the whole assembly haspreviously been removed from bottom plate 11. The needle 33 is insertedinto the chuck until the hole 33a in the needle is about /3 inch abovethe top of the threaded portion 47. Knurled nut 38 is then tightened.

The entire chuck unit assembly, by use of main knob 43, is threaded intobottom plate 11 until the tube is pierced.

At this time the centrifuge tube may drain either by gravity, since itis open to atmospheric pressure through tube 22, or by applying a smallamount of air pressure through tube 22. This air pressure may easily beapplied by attaching a rubber tube to hold-down tube 22.

If upward flow is desired, the same steps as above are essentially usedin placing the tube 14 in the fractionator. However, a length ofpolyethylene tubing 50' is first pulled through the aperture 26 inrubber cap 21 until the end of the tubing is flush with the dome-shapeddepression 24. The cap 21 is placed on the centrifuge tube and thepolyethylene tubing is fed up through rigid tube 22 out through its end.The same procedure is followed thereafter as above.

In order to cause upward flow into the polyethylene tube contained byrigid tube 22 a dense fluid, heavier than any of the fluid already inthe centrifuge tube, is

applied through the needle 33 thus displacing the gradient layersupwardly through the dome shaped rubber cap into the polyethylenetubing. This is usually done by using a small peristaltic type pump.

If desired, the depth of penetration of needle 33 into the tube 14 iseasily adjusted by initially adjusting the amount the needle protrudesfrom portion 47. In this manner specific layers that are present in theultra-centrifuge tubes may be selectively extracted.

Thus, in conclusion the present invention provides an improvedfractionator which accommodates different size ultra-centrifuge tubes,is simple in operation, and provides for either upward or downward flowtype operation.

I claim:

1. A fractionator for the removal of gradient layers from preparativeultra-centrifuge tubes comprising; a bottom plate having an aperturedcenter portion adapted for receiving one of said tubes, a plurality ofsupport posts upwardly extending from said bottom plate and defining acylindrical volume having a predetermined diameter, spacer means adaptedto be slid over said posts and providing abutments, a plurality ofadaptor rings having an outer diameter substantially equal to saidpredetermined diameter and an inner diameter equal to the tube diameter,said rings resting on said abutments provided by said spacer means,means adapted to hold down said tube against said center portionincluding a cap for sealing said tube, a top plate afiixed to saidposts, a rigid tube extending through said top plate into contact withsaid sealing cap, and means for fixedly securing said rigid tube to saidtop plate.

2. A fractionator as in claim 1 in which said cap is composed ofresilient material.

3. A fractionator as in claim 2 in which said portion of said cap whichcontacts said tube is dome shaped.

4. A fractionator as in claim 1 in which said center portion of saidbottom plate includes resilient means for receiving said tubes.

5. A fractionator as in claim 1 in which said top plate is aifixed tosaid posts by a twist-lock type action.

6. A fractionator as in claim 1 together with needle means forpenetrating said tube and a chuck assembly for retaining said needle,said chuck assembly being screwed into said aperture of said bottomplate whereby said needle means pierces said tube.

7. A fractionator as in claim 6 together with means included in saidchuck assembly for adjusting the depth of penetration into said tube ofsaid needle means.

8. A fractionator as in claim 1 in which said sealing cap includes anaperture for communication between said rigid tube and the interior of acentrifuge tube whereby a pressure head can be applied to liquid in suchtube.

References Cited UNITED STATES PATENTS 2,604,261 7/1952 Silverstolpe233-26 3,081,029 3/1963 Gauslaa 233--26 3,361,343 1/1968 Lerner 233263,365,102 1/1968 Castleberry 222-83.5 3,366,278 1/1968 Fobes 222-82SAMUEL F. COLEMAN, Primary Examiner U .8. Cl. X.R.

